The present invention relates to plasma sources for use in the performance of plasma-assisted processes, including deposition and etching processes performed on substrates in processing chambers. The invention particularly relates to plasma sources which allow processing of large area substrates.
There is a demand for plasma sources that will enable processes of the above-mentioned type to be performed on large size wafers and even more so for flat panel display processing. There are indications in the industry that efforts will be made to manufacture flat panel displays measuring 1 meter on a side and plasma-assisted processing of such substrates will require higher plasma ion density levels than are produced in existing systems. Plasma-assisted processing of such large area substrates requires both high plasma density and high pumping speed to achieve high processing rates.
In plasma sources of the type described above, the plasma deposition or etching rate will depend on the ion flux, or ion density, as long as the process gas throughput, or pumping speed, satisfies the processing chamber requirements. Therefore, the achievement of satisfactory processing rates for large area substrates requires both the gas throughput and the ion flux be sufficiently high.
In addition, a plasma source having the requisite large dimensions must withstand a considerable force from atmospheric pressure and must be capable of providing an optimum geometry for creation of an electric field that will provide a uniform plasma inside the processing chamber of the source.